Intramedullar Fixtures for Repair of Broken Bones
Intramedullar fixtures for use in repair of broken bones are well known in the art. Such fixtures, which generally have the form of long, narrow nails, are inserted longitudinally into the bone's intramedullar cavity, so as to connect together and jointly brace two or more sections of a severely fractured bone, and thereby promote healing.
A fixture of this type must have a radial diameter large enough to firmly and rigidly hold its position after insertion. The problem of holding the fixture in position is complicated by the fact that the intramedullar cavity of most long bones is not uniform, but is, rather, narrow at the middle of the bone and flares out at the ends. The problem is further complicated by the fact that a rod inserted into such canal does not normally provide stabilization for rotational and bending movement.
Frequently, the bone medulla must be reamed out before insertion of the fixture, to make room for the fixture therein. Such reaming destroys tissue within the bone and may consequently retard proper healing. Therefore, various intramedullar nails and fixtures have been designed to have a narrow shape during insertion and then to expand radially outward to fit the shape of the intramedullar cavity and hold firmly therein.
For example, U.S. Pat. No. 4,204,531 to Aginsky, which is incorporated herein by reference, describes an intramedullar nail with an expanding mechanism. The nail includes an outer tubular sheath, a rod-shaped element longitudinally movable in the sheath, and an expandable element having two or more spreadable longitudinal branches at the front (inner) end of the nail. The nail is inserted into the medullar cavity of a bone, front end first, leaving the rear end of the nail to protrude out of the end of the bone. The rod-shaped element is then pulled back, causing the branches of the expander element to spread radially outward, thereby anchoring the front end of the nail within the intramedullar cavity.
Similarly, U.S. Pat. No. 4,854,312 to Raftopoulous et al., which is also incorporated herein by reference, describes an expanding intramedullar nail. The nail is formed of two elongate members. A first one of the members has an articulated channel, which slidably engages the second member. After the nail is inserted into the intramedullar cavity, the second member is slid longitudinally relative to the first, causing the end of the second member to bend, so that the nail spreads laterally within the cavity and is anchored in place.
U.S. Pat. No. 4,313,434 to Segal, which is incorporated herein by reference, describes a method for fixation of fracture of long bones using a flexible, inflatable bladder inside the intramedullar cavity. A small opening is drilled in the bone, and the bladder is inserted through the hole into the intramedullar cavity. The bladder is then inflated with sterile air and sealed, to fixate the bone. After the fracture has healed, the bladder is deflated and removed.
U.S. Pat. Nos. 5,423,850 and 5,480,400 both to Berger, which are incorporated herein by reference, describe methods and devices of bone fixation using a balloon catheter. The catheter, with the deflated balloon at its distal end, is inserted into the intramedullar cavity, past the fracture site. In the '850 Patent, the balloon is inserted by guiding it along guide wires that are fed through the cavity, before introducing the catheter. Once fully inserted in the cavity, the balloon is inflated to anchor it in place, and the catheter is tightened against the balloon to provide compression to the fracture.
The intramedullar fixtures and methods of implantation thereof that are described in all of the above-mentioned patents require that a portion of the expandable intramedullar fixture be left protruding through the patient's skin. Such protruding portions, however, increase the likelihood of postoperative infection and interfere with mobilization of the bone. Accordingly, it is an object of the present invention to provide methods and devices which eliminate the need for such protrusions.
In addition to fracture of large bones, fracture of long small bones is also a very common occurrence. However, a simple treatment which allows early mobilization with fracture stabilization is not currently available.
Varela and Carr in an article entitled "Closed Intramedullary Pinning of Metacarpal and Phalanx Fractures," in Orthopedics 13 (2), 213-215 (1990), which is incorporated herewith by reference, describe one method for fixation of finger fractures using K-wires. To fixate a fractured finger bone, several such wires, slightly bent, are inserted one after another into the intramedullar cavity. Each wire is inserted through a respective hole drilled near one end of the bone. Typically, between two and five wires are needed to fixate the bone. After insertion, the wires are cut off flush with the bone surface, and the skin is closed over the insertion site.
However, the treatment of choice today for fractured small tubular bones is the insertion of a thin metal rod (intramedullary nailing). To prevent this rod from moving, an edge of the rod is left projecting from outside the bone, such as is done in metatarsal bone fracture nailing where the end of the rod projects out of the finger tip. This fixation, however, prevents the patient from using the finger or the broken bone limb. It also does not allow good rotational stabilization. In addition, it can also result in infection due to communication between the bone medulla and the exterior of the body.
Some patents and methods for the fixation of small bones without use of protruding rods currently exist in the art. Examples include, for example, Lewis, R. C., Jr., Nordyke, M., Duncan, K., Clinical Orthopedics Related Research, 1987, 214 (85-92); Nordyke, M. D., Lewis, R. C., Janssen, H. F., Duncan, K. H. J. of Hand Surgery, 1988, 13/11 (128-134); Varela, C. D., Carr, J. B., Orthopedics, 1990, 13/2: 213-215; and, WO 94/12112, U.S. Pat. No. 4,204,531, and U.S. Pat. No. 4,854,312.
One method in particular is described in an article "Expandable Intramedullary Device for the Treatment of Fractures in the Hand", Royce C. Lewis et al., Clinical Orthopedics and Related Research, Tech. Ortho., 1989, 1:18-91. In this article, an expandable intramedullary nail is inserted after the fractured bone is opened and the nail is inserted through the broken part. The nail is inserted through the fracture and not through the bone extremities. Yet, there still exists a need for a percutaneous minimal trauma insertion of an internal fixator for small bones which does not necessitate exposure of the bone surface.
Intramedullar nailing through the finger tip is also discussed in the article "Closed intramedullary pinning of metacarpal fractures", Varela, C. D.; Carr, J. B., Orthopedics, 1990, 13/2: 213-215. However, this nailing does not involve an expandable nail.
Numerous of the bone fixation patents mentioned above involve implantation of different metal devices (i.e., Nitinol, Titanium, etc.). Another possibility is to use a detachable inflatable balloon as an expandable intramedullary bone fixator. There are patents that exist today for bone fixation with a balloon, but these do not provide intramedullary nailing. They provide only a joining effect as in the pulling of one broken bone towards the other. Examples of these include U.S. Pat. Nos. 5,423,850 and 5,480,400 (described above).
Accordingly, a variety of significant shortcomings exist in the present art of fracture stabilization. To address these problems, the present inventors have provided an intramedullary nailing which is accomplished using a variety of inventions desribed below. For example, by using a detachable intramedullary balloon located at the middle of the fracture, and extended across both bone segments, a improved device is provided which addresses the numerous shortcomings of the prior art. Such devices provide the patient with a rapid post-surgery fracture stabilization resulting in mobilization of the limb and reduced chance for infection, as well as the possibility of removal after bone healing, if needed.
Intervertebral Disc Ablation and Spacer Placement
Back pain is a widespread ailment which is often attributed to disc pathologies and vertebral instability. Nowadays, the treatment of choice of spinal fusion involves disc removal followed by implantation of a plate with or without screws into the intervertebral space (See e.g., U.S. Pat. No. 5,520,690, U.S. Pat. No. 5,522,816, and U.S. Pat. No. 5,529,899). The procedure also involves implantation of a bone graft in the intervertebral space.
Patents and applications employing artificial intervertebral discs currently exist, although they have not yet been proven successful in patients (U.S. Pat. No. 4,759,769; WO 92/14423; WO 90/00037; WO 96/37170). Existing treatments involve introductory surgery for removal of the original spinal disc tissue and placement of the intervertebral support. An intervertebral spacer and stabilizer is placed within the intervertebral space followed by the removal of the damaged disc and cleaning of the intervertebral bone surfaces by use of different cutters and retractors (U.S. Pat. No. 4,904,260 and U.S. Pat. No. 5,645,598 for example). A bone graft is then implanted to facilitate spine fusion.
All procedures utilizing the above method require actual opening and dissection of the back and/or the abdomen or performing the procedure laparoscopically. Accordingly, there is currently a need in the art for a percutaneous non-laparoscopic type minimally invasive technique to facilitate and improve the current method for spine fusion.
In addition, the disc ablation procedure may involve the interposition of a spacer in the intervertebral space to support the vertebrae until spine fusion is achieved by osteogenesis. The existing spacers are constructed with a fixed diameter according to the space needed to be kept in the intervertebral area. Although one spacer has been disclosed which expands by rotating a screw, it only expands upwards and downwards, and therefore still has a large insertion profile. This does not allow for the insertion of the device percutaneously in a minimally invasive technique. As discussed in greater detail below, there is a need for a spacer or prosthesis that is created with a small diameter and which can expand radially once implanted. In addition, as also discussed below, there is also a need for an intervertebral tissue extractor which can likewise function percutaneously for use in the procedures described.
Intervertebral Disc Prostheses
Intervertebral disc prostheses are also known in the art. Such a prosthesis is generally inserted into the intervertebral space following the removal of all or a part of the disc matter from the space. Upon insertion, the prosthesis holds two adjacent vertebrae apart from each other, so as to maintain the vertebrae in an anatomically correct spacing and orientation. Following surgery to implant the prosthesis, bone generally grows from the vertebrae into and around the prosthesis, thereby holding the prosthesis firmly in place and preventing undesirable motion of the vertebrae relative to each another.
U.S. Pat. Nos. 4,772,287 and 4,904,260 to Ray et al., which are incorporated herein by reference, describe prosthetic disc capsules having a generally cylindrical shape and containing a gel material having properties similar to those of the disc matter. After removal of a portion of the disc matter, two such prosthetic capsules are implanted in the disc space, one on either side of the sagittal axis of the spine. The capsules may be implanted in a deflated state and then inflated with the gel to a pressure sufficient to hold the adjoining vertebrae apart.
To implant the prosthetic disc capsules in the disc space, it is necessary to open the patient's back and perform a partial laminectomy to gain access to the disc space. Such open laminectomy is a major surgical procedure, with attendant risks, side effects and long recovery time. Other disc prostheses, as described, for example, in U.S. Pat. Nos. 3,875,595, 4,349,921, 3,867,728, 4,554,914, 4,309,777, 3,426,364, and 4,636,217, and incorporated herein by reference, similarly require major surgery for implantation thereof.
In response to the risks and lengthy recovery period associated with open surgery for treatment of bulging or herniated discs, an alternative, minimally-invasive surgical technique of percutaneous diskectomy has been developed. In percutaneous diskectomy, a narrow cannula is inserted into the disc space in a lateral approach through a small incision in the patient's side. The lateral approach to the disc obviates the need to cut through bone and/or substantial amounts of muscle, as required by other surgical methods known in the art. Surgical tools are passed through the cannula to cut away and remove disc material, so as to relieve the outward pressure of the disc on surrounding nerves and thus to alleviate the pain caused by the bulging or herniated disc.
Percutaneous diskectomy can be performed as an outpatient procedure and, when successful, allows the patient to return to full activity after only a short recovery period. The procedure is successful only in about 70% of cases or less, however, and does not allow the full range of treatment afforded by open back surgery. For example, disc prostheses and methods of implantation of such prostheses that are known in the art are not suitable for use in the percutaneous approach.
The vertebrate spine is the axis of the skeleton, on which the body parts hang. The bony vertebral bodies of the spine are separated by intravertebral discs, which serve as a cushion between vertebral segments of the axial skeleton. These discs comprise a fibrous annulus and a nucleus, which is a gel-like substance, contained within the annulus. A disc herniation occurs when the tissue of the nucleus bulges out of the annulus. The herniated nucleus may exert pressure on a spinal nerve adjacent to the disc, resulting in pain or loss of muscle control. The normal procedure in such cases is to remove the herniated disc tissue in open surgery, but this is a major procedure with long recovery and potentially serious side effects.
In response to the dangers and complications of open spinal surgery, minimally invasive procedures for removal of herniated tissue have been developed. One type of such procedure as described above, is percutaneous diskectomy, in which herniated tissue of the nucleus of the disc is removed from the patient's body. Apparatus for such procedures is described, for example, in U.S. Pat. No. 5,131,382, which is incorporated herein by reference. The nuclear tissue is removed thorough a cannula, which is inserted through a small incision, preferably in the patient's side, into the intervertebral space. By making the incision as small as possible and entering the body laterally, rather than dorsally, trauma to the patient is minimized. Removal of the herniated tissue is a long process, however, frequently requiring removal and reinsertion of resection tools many times.
In some diskectomy procedures, after the tissue is removed, a disc prosthesis is inserted to replace the nucleus and possibly the annulus, as described above, and in PCT publication WO 96/11643 for example, whose disclosure is incorporated herein by reference. Generally, it is desired that the two adjacent vertebrae fuse together, around the prosthesis. In order to facilitate insertion of the prosthesis and encourage subsequent bone fusion, the disc tissue should be thoroughly cleaned out during diskectomy. However, percutaneous diskectomy procedures and devices known in the art do not generally achieve such thorough cleaning.
Prosthesis Loosening
As discussed herein, medical implants such as orthopedic fixation devices can be inserted into the body in a small diameter state, and, once inserted, can be inflated to a larger diameter and/or a longer length. In U.S. Pat. No. 5,376,123, for example, Dr. Klaue teaches a hip prosthesis having an inflatable member to firmly fixate the implant into the femoral bone medulla. Moreover, as discussed below in greater depth, the present inventors have provided novel devices, including intramedullary nails, spine cages, and other inflatable implants which can be inserted into the body in a minimally invasive technique in a small diameter state and then inflated with a non-compressible material to a larger diameter state.
In the past, prostheses have often shown a decrease in effectiveness over time due to loosening effects. For example, hip prosthesis implants and knee prosthesis implants have shown a high rate of implant loosening over time. This loosening is caused by a space which is created between the implant shaft in the area where it is attached to the bone. This complication, which usually appears 1-13 years after implantation, requires a second operation to eliminate the loosening. Likewise, it is known that bone implant complications generally can include loosening between the implant and the bone, causing relative movement between the bone and the implant, and forcing another operation to achieve good bone to implant fixation.
As a result, there is a need for a device which can be provided to prevent movement between an implant and the bone, to optimize the success and fixation of the implant over time. To address this need, the present inventors have provided a non-invasive technique and related device which allows a prosthesis to be changed in diameter and/or length whenever needed. In this manner, the need for another procedure to correct loosening (which usually appears within a few years) can be eliminated.
Electrocautery Probes
Electrocautery probes are used in a wide range of surgical procedures, particularly in less-invasive and minimally-invasive surgery. One of the most common uses of such probes is in surgical treatment to relieve urinary obstruction due to enlargement generally known as transurethral resection of the prostate (TURP).
FIG. 21 is a schematic diagram showing a prior art electrosurgical probe 200 for use in TURP and other procedures. Such probes are distributed, for example, by Olympus Optical Company, of Tokyo, and Karl Storz GmbH, of Tuttlingen, Germany. Probe 200 comprises a shaft 201 having a wire loop 202 of adjustable size, protruding from a distal end 203 of the shaft. Shaft 201 is connected at its proximal end 204 to a handle 205, which is used by a surgeon to manipulate and control the probe. Wire loop 202 is connected via a wire 206 to an electrosurgical power source 207, which supplies RF energy to the loop.
FIG. 22 is a schematic, sectional illustration showing the use of probe 200 in a TURP procedure, as is known in the art. Shaft 201 of probe 200 is inserted through urethra 209 of a subject so that distal end 203 thereof is within prostatic urethra 208, i.e., the portion of urethra 209 surrounded by prostate gland 210. Power source 207 is activated, so that an electrical current passes through wire 206 and loop 202. The current passes from loop 202 through the tissue or prostate 210 which is adjacent to the loop, thus resecting the tissue. The current returns via a grounding pad (not shown in the figures). The surgeon draws loop 202 back and forth along prostatic urethra 208, as indicated by an arrow 211 in the figure, so as to resect a "chip" of tissue from prostate 210 along the entire length of the prostatic urethra. This procedure is repeated until prostatic urethra 208 and prostate gland 210 have been completely resected.
In resecting prostate 210, the surgeon must take great care that electrocautery loop 202 not contact urethral sphincter 212, which is proximally adjacent prostatic urethra 208, as shown in FIG. 22. If loop 202 is drawn too far proximally along the direction of arrow 211, it will resect sphincter 212 and/or nerves associated therewith, with the result that the subject may become permanently and irreversibly incontinent.